This invention relates to a statistic multiplex transmission system. More particularly, this invention relates to a multiplex gateway apparatus for executing statistic multiplex transmission of images in public ATM inter-network communication.
Means for executing ATM transmission of image signals to which variable rate encoding is applied by an MPEG2 system using a terminal stipulated by ITU-T recommendation, H.310 (hereinafter called merely the “terminal device”) is known generally. In other words, when ATM transmission is performed, image transmission means is known that connects a local area ATM network laid down in a first area to a local area ATM network laid down in a second area through a public ATM network, and transmits images.
An image ATM transmission according to the prior art will be explained with reference to FIG. 1.
In the example shown in FIG. 1, the image terminal device uses an H.310 terminal stipulated in H.310 of the ITU-T recommendation. It will be assumed hereby that a CPN local area network n is laid down in a first area and a CPN local area network p is laid down in a second area. The CPN local area network n and the CPN local area network p are connected to each other through a B-ISDN public network o. H.310 terminals 31 to 33 are connected to the CPN local, area network n as shown in FIG. 1. H.310 terminals 34 to 36 are connected to the CPN local area network p. The H.310 terminals 31 to 33 are connected to any of the H.310 terminals through the local area ATM network—public ATM network—local area ATM network. For example, the H.310 terminals 31 to 33 are connected to any of the H.310 terminals through the local area ATM network—public ATM network—local area ATM network, respectively, as shown in FIG. 1. In other words, each H.310 terminal is ATM connected independently in the point-to-point connection through the local area ATM network—public ATM network—local area ATM network.
In image transmission according to the prior art described above, the image signal that is VBR-encoded at each H.310 terminal by an MPEG2 system is merely ATM connected independently. Therefore, a statistic multiplex effect cannot be imparted to the image signal outputted from each H.310 terminal. In other words, the image transmission system using the H.310 terminal according to, the prior art involves the problem that the statistic multiplex effect cannot be acquired because each H.310 terminal is connected independently in the point-to-point connection.